Electronics Forum | Thu Apr 22 06:42:03 EDT 2004 | Chris Lampron
Adam, What is the pad finish on the flex circuit? Is this the only component that you are having problems with? (on this Flex)If this is the only problem area on the flex (assuming there is more than one component)then that would lead me towards the
Electronics Forum | Thu Sep 16 01:54:46 EDT 2010 | sachu_70
Hi Gani, Immersion Ag finish has lesser shelf life as it can get more easily oxidized on exposure. However, I see concern in your Reflow profile. A few questions: Have you compared your reflow profile to the solder paste manufacturer's recommended pr
Electronics Forum | Wed Nov 06 03:51:28 EST 2013 | cuperpeter
Hi rob, Thank you very much for your response. Profiling was made exactly on the pad, which showed dewetting, so the values are mentioned for this pad. PCB's is about a week old. It is possible that the surface of pads is already oxidized? I will t
Electronics Forum | Tue Nov 05 09:57:45 EST 2013 | cuperpeter
Hello All, We have a problem with dewetting of solder paste. Problem is most visible on the pads without components (see attached pictures) and occurs randomly, 20% of PCB's. Pcb supplier sent us a cross-section of pads with thickness of Cu, Ni and
Electronics Forum | Wed Nov 06 10:03:59 EST 2013 | rgduval
Hi, Peter, I'm not an authority on surface finish thickness, and it's effect on reflowing, so, I can't advise on that front. If the boards are a week old, and ENIG, I would not suspect surface contamination. It's always a consideration, of course,
Electronics Forum | Tue Nov 05 12:34:54 EST 2013 | rgduval
3-6 months, say, depending on the environment), I might consider a ramp-soak-spike profile to allow sufficient time for the flux to clean any potential contaminants. Cheers, ..rob
Electronics Forum | Fri Apr 23 13:31:20 EDT 2004 | russ
The toes of leaded devices are problematic in fillet formation. A lot of the time they have the copper from the lead exposed so it becomes oxidized and won't readily take solder. Normally this is of no concern if the heel and side fillets are forme
Electronics Forum | Tue Apr 11 10:30:46 EDT 2000 | Jeremy Smith
I am having a problem with some joints on a 100 pin pqfp and few different soics on one particular board. When viewed a 8x with a "Mantis" inspection scope the joints look as though they wetted to the ic leg but when probed the leg will pop loose.
Electronics Forum | Mon Nov 12 01:18:29 EST 2007 | sin4d
Hi, ALL I experience some QFP with wetting issue on the heel of the lead. There is no fillet wetting on the heel which causes reject bt the customer, but not all the QFP. Could anyone pls help what is the causes of this problem, it is due to oxidati
Electronics Forum | Mon Nov 12 19:47:33 EST 2007 | sin4d
Hi, Thanks. Waitng for your reponse. BTW, if I were to perform a test as below will this give me some result to indicate if the component is defective. 1) Print solder paste on plain PCB without copper track. 2) Mount the QFP & reflow 3) If the sol
